Posted
by
Soulskill
on Wednesday April 15, 2009 @05:11AM
from the do-they-come-with-curved-sharks dept.

Urchin writes "Laser beams just gained a new property — they can curve through space. That's what happens when ultrashort laser pulses pass through a phase pattern mask and a lens, which together shift the most intense region of the beam from the center to the right-hand side. The asymmetry in the pulse causes it to drift progressively further to the right along an arc as it travels. The laser beam is so intense that it ionizes the air it passes through to create a curved plasma channel. Those kinds of channels can be up to 100 meters long — direct them at thunderclouds and they could first trigger lightning to spark and then act as a convenient but short-lived lightning rod to guide it safely to the ground, according to some researchers."

"Yeah, curving lasers, very viable"."Lasers shoot straight, stupid!""So this beam is some kind of plasma or what? Laser? Are you kidding?"Now they will all see! My sharks will be able to shoot lasers from behind a corner!

"Yeah, curving lasers, very viable".
"Lasers shoot straight, stupid!"
"So this beam is some kind of plasma or what? Laser? Are you kidding?"
Now they will all see! My sharks will be able to shoot lasers from behind a corner!

Raiden II, Schmaiden Spoo [wordpress.com]. Also let us not forget to order the French Fries [wikipedia.org] (I couldn't find a good screenshot, but some of you surely remember "french fries and onion rings" - homing laser and super blaster.)

I can't really imagine a practical use for this (a lightning rod seems like a much cheaper solution) but it's pretty nifty science.

Then You are not imagining hard enough. Cheaper or not cheaper, it depends on the height of the lightning rod. Higher the tip, wider the safety zone - we could save on individual lightning rods and current surge ducts. Eventually, maybe we could tap on the charged layers of atmosphere and drain them to harvest energy. Perhaps we could "puncture" (short circuit) cumulonimbus clouds in controlled fashion and thus trigger hailstorms before they encroach crop-farming areas. We could use very high plasma columns as SLF vertical ground plane antennas. We could form free-space atmospheric plasma channels to be used as very high voltage/low current power lines bridging across great distances without a single power line tower in between. We could tase tanks on the field, warships on the sea and even airplanes in the air (using two opposite high voltage sources from two distant points simultaneously). We could also tase civilians, steel-frame buildings etc. but I hope we wouldn't. We could create giant radius induction loops in the air for whichever purpose. Ah, if only Tesla was still with us today, he would probably found myriad of cool applications for this...

If this becomes a standard response to thunderstorms, it won't be long before people blame the government when they or their property get hit by lightening. Hell, discrimination lawsuits could emerge, depending on how the government allocates its resources. And if this is a private service, expect civil lawsuits.

It is fortunate that lasers and sharks go together on/., for the lawyers could end up profiting from these suggested uses.

I'm glad we have recourse to lawyers to recoup damages when people damage each other. I'm not glad that frivolous lawyers, who repeatedly bring cases without evidence, facts, logic or legal basis, keep their licenses. But I want us to close the "bad lawyers" loopholes, not ignore new methods to cope with our environment, even if there's some risk of damage we'll also have to cope with.

I'd be more interested in the effect of that energy no longer existing in the atmosphere... what if we destroy the Ionisphere by accident? We'd be stuck with nothing but line of sight and sattelite communications. What is if prevents certain types of clouds from forming which turns certain parts of the world into deserts?

We harvested the energy in hydrocarbons, and then discovered later it had implications. People propose wind power (which would harvest energy from our weather) without any implications c

The lightening rod is just for silly editors. If the idea works, it is a thundercloud discharger, grounding it. The idea being that it would stop strikes where you don't want them.

A lightening rod works after the fact and only on a very small area.

Say a thundercloud approaches, you can A: have lots of very tall spikes penetrate it so it discharges. B: create a grounding effect with some kind of plasma arc or C: put lightening rods all along the storms path hoping that the thunder will hit the rod, not som

This is not a "thundercloud discharger" unless your thundercloud is within 100 meters of the ground. They aren't, and most of those who are get called "tornadoes", but we can use blades of curved ionized air to cover a building's roof. So it could be used as a local lightning guide.
And if it glows, it can also be used as decoration.

We could mount the device on a platform fired from an aircraft, with a parachute, and a long grounding cable fired into the ground from the platform before the plasma fires at the lightning cloud. So county/municipal helicopters or cargo planes could do this work.

We could mount the device on a platform fired from an aircraft, with a parachute, and a long grounding cable fired into the ground from the platform before the plasma fires at the lightning cloud. So county/municipal helicopters or cargo planes could do this work.

So we run 3,000 meters of cable to the ground and use lasers to add another 100 meters of range? 3,100 meters of cable would be simpler.

If so, why indeed are we messing with these lasers at all? Why don't we tap lightning clouds reliably for power that way?

Lightning represents an enormous amount of power. According to Wikipedia, the peak output of a lightning bolt is about a terawatt. Whether or not that's accurate, it's a lot of power to capture and store in a useful way in a tiny fraction of a second.

I saw once the sacrificial boxes they have attached to the lightning rods at the datacentre of the company I work for. A Colorado lightning

Lightning researchers use a rocket to carry up a thin wire. All that's needed is an encouraging guide for lightning. But we don't have technology to convert much of that power into a useful form.

Someone mentioned 1 terawatt in a lightning bolt. OK, so that's equivalent to 10,000 100MW power plants. But the lightning bolt is brief; being generous, let's say it lasts a second. After 10,000 seconds the power plants have matched the power. That's 2.78 hours. So in this region, if you have a 100% conver

Say a thundercloud approaches, you can A: have lots of very tall spikes penetrate it so it discharges. B: create a grounding effect with some kind of plasma arc or C: put lightening rods[1] all along the storms path hoping that the thunder will hit the rod, not something else[2].

Actually...a lightening rods primary job IS to discharge without a strike.

Lightening is caused by electrical charge difference between clouds and the ground. Electrons tend to build up on higher points, until the difference is great enough to create an arc. Pointed metal poles actually allow electrons to bleed off, which actually prevents most strikes. Only as a secondary job does a lightening rod safely carry the current to ground if struck.

A few the nice features of the airy beam: the plasma conduit keeps the beam in focus; it tends to be self-healing, which means that small objects such as raindrops will not interfere with the overall path; the light from the plasma pulse does not propagate in the same direction as the beam, so it won't burn out your laser detector at the other end.

These features could make it very useful for communications purposes.

Another use which was mentioned was high-altitude spectroscopy. Instead of needing a sam

I used to work on this technology. The justification for it is really simple. If you could prevent just one lightning induced internet or power outage the amount of money saved would more than pay for all the research to date.

Under conditions When it works these systems are more effective than lightning rods. But to make these things ubiquitously functional and dependable is not a simple matter.

The airy beam decribed here I believe is just a variation of the old axiconic focus concept. With an axicon the

Those kinds of channels can be up to 100 meters long -- direct them at thunderclouds and they could first trigger lightning to spark and then act as a convenient but short-lived lightning rod to guide it safely to the ground, according to some researchers
Direct them at people, and you can hit them with a laser _and_ send a couple of thousand volts through the resulting ionized air at almost the same time. Sounds like fun, doesn't it?

Ah, but later on in the Sharkticon pit they talk about "photon charges" with regards to their ammo, which could very well imply lasers. Since this is about robots and sci-fi-ish stuff, we must presume that it's all internally consistent!

They just put so many photons into their laser blasts that the blasts can't move that fast anymore. In fact, if they'd put any more photons in, air friction would cause the blasts to burn up before they reach their target.

i guess he was thinking about conservation of energy and momentum?
shooting something with momentum (yes, light has momentum) should make it go in a straight line, not a curved one, unless other forces are also involved, like in refraction by the atmosphere for example.
In space, no atmosphere, so maybe no curved lasers?

Ah, so you reckon the summary wasn't talking about space as in "all that regions outside the Earth's atmosphere" but was talking about space as in "the limitless three-dimensional expanse where all matter exists" just so we didn't get confused with lasers that curve through time?:)

Do I need to point out the obvious incompatibility between the two statements?

This is what high energy "space war" lasers--or more precisely the beam aiming/focusing systems--have been fighting with for a long time when dealing with the atmosphere. Send a very high powered beam through the atmosphere... You get ionization and heating. The center of the beam heats/ionizes more rapidly. That causes defocusing or "thermal bloom". Air (wind) traveling through the beam has a greater distance to travel through the center of the beam than at the edges, resulting in greater heating/ioniz

From the coverage in cited New Scientist article, it isn't clear that curved laser beams have any advantage in triggering lightning over straight beams. As it is said, it would be fun to see that curved lightning. Sounds rather like pure fun, no big scientific breakthrough, as it comes to atmosphere control.

But the power is on for only a brief fraction of a second, so the total power is actually small, only enough to power a 100-watt light bulb for six months

What world do you live in where 1.5GJ (438kWh) is not a lot of energy? It's enough to power my house for almost two months. Storing it is obviously difficult, but it may be possible with a battery of ultracaps, and is made a lot easier if you can choose when and where the lightning strikes...

Actually, the opposite has already been used, there is a very bulky taser that instead of using darts (I think you're talking about stun guns, right?) uses lasers to ionize a path. With this tech you could make it curve and zap those geeks from a distance.

Normally the refractive index of a material is quoted as a constant. However, light radiation will slightly distort the electron levels of the material they are passing through, and this will have effect the refractive index. Normally this effect is very tiny. However, if you design high-power lasers, then it can become a nuisance. If you have a bright spot to your beam, then this will locally raise the refractive index. This will, in turn, cause the light to come to a line focus, which raises the intensity even more. If you do not design high-power optics to account for this, then a flat, uniform beam of light can spontaneously divide into a set of filamentary hot spots, which can smash your expensive optics.

There is another process, more usually associated with high-power ion beams. An ion beam that travels a long distance in air can twist like a garden hose squirting water. The ion beam heats up the air it is passing through, which creates a kind of pipe through the air as the hot atoms move away. This is a nuisance if you want to make the beam go in a straight line. One way of keeping an ion-beam weapon firing straight is to put a laser pre-pulse to heat a straight line through the air for the ion beam to travel down.

There is another process, more usually associated with high-power ion beams. An ion beam that travels a long distance in air can twist like a garden hose squirting water. The ion beam heats up the air it is passing through, which creates a kind of pipe through the air as the hot atoms move away. This is a nuisance if you want to make the beam go in a straight line. One way of keeping an ion-beam weapon firing straight is to put a laser pre-pulse to heat a straight line through the air for the ion beam to travel down.

The 'hosepiping' usually happens over a longer distances. It is needed if you want to try and hit an incoming missile at a few kilometers. However, the squiggling beams in 'Ghostbusters' did have the right sort of motion, and protons are lighter than other ions and more easily scattered...

Well, well, well. Thanks for that. I wonder if they knew someone in the military, or maybe they just made the beams squiggle because that's what electric arcs do.

Doc Emmett Brown could've used something like this. Then he wouldn't have had to swindle the Libyans, and he wouldn't have gotten shot for it. Kinda makes you wonder if we can attach one of these to a capacitor that can hold 1.21 JigaWatts (or several times that for several lighting strikes).

Christodoulides's team's work could be combined with his to help aim the laser pulses and plasma channels at specific targets, such as clouds, although he points out that the laser pulses can also be guided using mirrors. "But it would be fun to see curved lightning discharges," he says.

This article is cool up until the lightning bit. As the quote from TFA shows, there's absolutely no connection between the curved lasers and the technique for triggering lighting. As far as generating an ion channel goes, the curved laser does nothing a straight laser can't. The only connection between the otherwise completely disconnected bits of research is that the lightning guy commented on the curved laser stuff and essentially said that while using mirrors is more feasible in his project, using curved lasers would look cool.

Everytime someone comes up with an interesting discovery in science, people invariably ask what it's good for. Ditto for math. The problem is that a lot (most?) research is done for its own sake, to discover new things, rather than having any particular application in mind. History has shown that applications tend to come later, and in the places you least expect it, so it pays to just be curious. People thought group theory was just weird abstract shit until someone figured out how to use it in applied chemistry.

It's said when the need to immediately justify every new discovery has gotten to the point where an article needs to include a completely contrived and ridiculous application just to placate people.

The problem is that a lot (most?) research is done for its own sake, to discover new things, rather than having any particular application in mind.

I know I'm stating the obvious here because you sound well-versed in the research field. While scientists are typically motivated to perform research to satisfy curiosity, etc. funding sources have very distinct agendas. Prior to 2000, it seemed like the best way to get your research funded was if the science had a military application. Hence, this charged part

I never knew that they created their own channels to travel through, though I guess it makes sense. I seem to recall scientists of yore once thinking that light traveled along its own self-generated aether. I guess plasma channels are kind of like that, so it would appear we've come full circle (Light creates its own medium to travel through, no it doesn't, it kind of does.)

Does anyone know if all light behaves this way or just lasers (Or lasers of a certain intensity)? Better yet, a resource that is (at

"I guess plasma channels are kind of like that, so it would appear we've come full circle (Light creates its own medium to travel through, no it doesn't, it kind of does.)"

Kind of stretching the point, do you think? I mean, light traveling through a vacuum wouldn't create a plasma channel. It happens it's passing through air, and the energy of the light modifies the properties of the air it's passing through. When a boat passes through the water and creates a wake in the water, is it 'kind of creating its o

So these plasma channels are more of a result of the light being there than something that guides their direction? If that is the case, how does shifting the intensity to one side cause it to curve?

Or is it more that light can influence its own path when traveling through a medium of a certain density? How much of an influence are we talking here? And is this the same principal behind refraction, or is that something else entirely?

I don't know, for sure, I'm not a physicist. All I was saying is that the statement made seemed to be that the light was somehow modifying the air (turning it into a plasma) - not creating something that wasn't there before.

The suggestions that straight beams could do the same are only partly right, and indicate who didn't read TFA. The concentration of the most intense part of the beam due to the curving mask and lens makes it more efficient than unaltered straight beams in creating ionized channels for a given beam strength. Something that did the same concentrating for straight beams would produce the same effect, but the fact remains that the curving mechanism would produce it as stated.

This looks like a clever anti shark plot to me. Eventually the curved beam will go all the way around and kill the shark itself. No thanks, I'm sticking to straight shooting lasers on my sharks. Nice try, Austin.

I don't really care about Austin powers. I surprised no on brought up the prospect of dressing up like an undead mage and calling lightning around you when there's a storm. How cool would that be? Now to make Molotov Cocktails that explode like arcane magic.

I would like to point out that the original 'Frankenstein' novel by Mary Shelley makes no statement connecting a lightning strike with animation of Dr. Frankenstein's golem. There is reference to a lightning striking a tree during his youth, and his amazement at natures power, but that is all.

Of course the laser beam don't need to curve to tame lightning. Presumably a mirror cheap enough to sacrific to a lightning strike could be moved to the approprate place, right? Even the researcher admits this is...

Kasparian says that in future, Christodoulides's team's work could be combined with his to help aim the laser pulses and plasma channels at specific targets, such as clouds, although he points out that the laser pulses can also be guided using mirrors. "But it would be fun to see curved lightnin